1. Field of the Disclosure
This disclosure relates generally to oilfield downhole tools and more particularly to methods and devices for cooling of bearings in drilling tools.
2. Description of the Related Art
To obtain hydrocarbons such as oil and gas, boreholes or wellbores are drilled by rotating a drill bit attached to the bottom of a BHA (also referred to herein as a “Bottom Hole Assembly” or (“BHA”). The BHA is attached to the bottom of a tubing, which is usually either a jointed rigid pipe or a relatively flexible spoolable tubing commonly referred to in the art as “coiled tubing.” The string comprising the tubing and the BHA is usually referred to as the “drill string.” When jointed pipe is utilized as the tubing, the drill bit is rotated by rotating the jointed pipe from the surface and/or by a mud motor contained in the BHA. In the case of a coiled tubing, the drill bit is rotated by the mud motor. During drilling, a drilling fluid (also referred to as the “mud”) is supplied under pressure into the tubing. A rotor of the mud motor is rotated by the drilling fluid passing through the BHA. A drive shaft connected to the motor and the drill bit rotates the drill bit. Some drill strings include steering devices that may utilize devices that have a rotating section and a non-rotating section.
The non-rotating section remains mostly stationary relative to the wellbore as the drill string rotates. The present disclosure addresses the need for effective cooling and/or lubrication of the interfaces between the rotating and non-rotating sections of such steering devices as well as other interfaces between rotating and non-rotating components along a drill string.